In a common storage product, a system architecture including a plurality of storage processors (SPs, also called processing nodes) attached with a shared disk is usually utilized to improve computing capability and input/output (IO) throughput of the storage product. The plurality of storage processors are connected via an internal communication interface and perform data synchronization with the internal communication interface. In a storage processor, there is usually a cache module for caching data to be written into the shared disk.
In a conventional scheme, such cache module may be only used for caching and synchronizing (e.g., with a peer SP) user data (namely, the data written into the shared disk) and may only be used by an upper module above the cache module. As a result, non-user data, such as mapping information of storage objects and metadata of a file system, is only stored in a local memory and will not be synchronized to a peer memory, which thereby might lead to inconsistent states of the processors. A lower module below the cache module cannot use the service provided by the cache module. Therefore, the data in the lower module cannot be cached conveniently. Moreover, when the system power supply fails, the data in the cache (e.g., the data which has not been written into the shared disk yet) might get lost.